fix: 修复下滑加载更多数据缓存问题

- 加载更多时追加数据到缓存而非覆盖
- 去重处理避免重复数据
- 确保缓存保存所有页数据

pages/index/index.js

@@ -738,15 +738,23 @@ Page({
         const totalPages = res.totalPages || Math.ceil(totalGoods / this.data.pageSize);
         const hasMoreData = page < totalPages && res.products.length > 0;
         
-        // 更新缓存
+        // 更新缓存（加载更多时追加数据）
         const updatedCache = { ...this.data.categoryQueryCache };
-        updatedCache[cacheKey] = res.products;
+        if (isLoadMore && updatedCache[cacheKey]) {
+          // 追加新数据到缓存
+          const existingIds = new Set(updatedCache[cacheKey].map(item => item.id));
+          const newProducts = res.products.filter(item => !existingIds.has(item.id));
+          updatedCache[cacheKey] = [...updatedCache[cacheKey], ...newProducts];
+        } else {
+          // 首次加载或刷新时替换缓存
+          updatedCache[cacheKey] = res.products;
+        }
         
         this.setData({ 
           hasMoreData,
           categoryQueryCache: updatedCache,
           lastDataTimestamp: now,
-          goodsCache: res.products
+          goodsCache: updatedCache[cacheKey]
         })
         
         this.processGoodsData(res.products, isLoadMore)